Improvement in making molds for castings



`UNITED STATES l PATENT OrmesC FRANOISAN. STILL, OF BUFFALO, NEW YORK.

Speciiication forming part of Letters Patent No. 4,803. dated October 7,1841i.

To all whom it nil/wy concern,.-

Beit known that I, FRANCIS N. STILL, of

Buffalo, in the county of Erie and State of New York, have invented anew and Improved Method of Molding for Castings; and I hereby declarethat the following is a full and exact description. y

The nature of myinvention consistsin using two patterns for one casting,and having those patterns placed with the reverse sides up,and madestationary in two separate Ilasks filled with plast-erot'paris. Myobject in using two patterns is that I may mold from concave and convexpatterns, such as cannot be divided or molded from a plate. My object inusing the two asks of plaster-of-paris is that I may get t'wo concaveand convex lsurfaces to lit each other perfectly, and at the same timelit the particular shape of the patterns, so that when atlask of sand isfilled upon each of them, taken off, and closed together, it will form aperfect mold from said patterns. I

To enable others skilled in the art to make and use my invention, I willproceedto de! scribe its construction and operation.

The two frames A and B in the accompanying drawings, are intended torepresent two separate flasks, which are made to fit each otherperfectly. I then ll the flask A with a putty made OI'plaster-Of-paris,as is seen at C, and place in one or more patterns, as I think i it mostconvenient, with a part of the pattern raised above the putty, as isseen at D. After the putty becomes set and hard, I put on a coat of oilto prevent the green putty from pression of the pattern D.

sticking to it. I then take the flask B, place it upon the ask A, andtill it with a green putty, press it down and let it remain until it becomes set and hard. I then take it off, having a perfect fit of the twoiiasks of plasterot paris, as is seen at C and E, and also an im- Ithentake my second patternand place it in the impression taken from thepattern D, as is seen at f. Thisy done, my patterns are completeandready for use. I now use the two flasks containing theplaster-ciparis and patterns as a stationary die, upon which I strikethe molds in sand for castings.' For example, I take a set of flasks,

as is common in molding, and fit them to the asks A and B, fill themwith sank, take them off, close them together, and this forms a perfeetmold of the patterns contained in the two asks of plaster-of-paris.

I do not claim molding from plain patterns, such as can be divided andmolded from eachY half, nor from such as can be molded in connectionwith a plate.

What I claim as myinvention, and desireto secure by Letters Patent, is-A Making the second pattern or patterns by taking an impression of therst upon plasterof-paris or other similar. substance, and placingduplicate patterns in the cavities made by the patterns of the first,substantially as herein described.

FRANCIS N. STILL. Vtnesses:

J. M. THAYER, Z. O. RoBBINs.

